How much HP does the 911 cooling fan cost?

[SpeedracerIndy]

Just wondering if anyone knows how much HP it takes to power the cooling fan for the engine. I have seen VW flat fours that have adopted the 911 cooling fan design, and I always hear that it is not a good idea because it robs so much HP. What would the "added" Horse power be if you unhooked the cooling fan.

Also, on a similar subject, how long would it take to cook the engine if the fan belt broke?

I remember reading it in Auto Motor & Sport, but I can't remember the figure I think it was 16, but as I said I can't really remember

Without the fan you still have the oil cooler in the front fender. I think it's not too dangerous to "crawl" home with a broken fan belt.

Hey just thought of something; how will our 911s sound without the air fan!? Scary.... It would be like drinking coffee without sugar in it

[dean]

Mikkel,
I think you are wrong about running without a fan. I think the motor will overheat very quickly.

[masraum]

I think the motor would overheat pretty quickly without the fan. The motor would probably overheat faster at low speeds because of the lack of airflow. At higher speeds there will be more airflow, but you'll also be making more heat. Either way it would be really bad.

[Chuck Moreland]

Definitey do not run the engine without a fan. You will quickly have a meltdown. You will do internal damage within minutes.

16 HP might be a reasonable estimate. A thread from awhile back showed a savings of 7hp peak just by running the fan at a slightly slower speed.

[Larry Harris]

Sugar in your coffee!! My God man.

[Bill Verburg]

cooling fan thread

[Jocke]

Why does it take so much HP?

/Jocke

[alf]

Along the same lines, how many horses would i free up if i disconnect the belt to the AC Compressor?

Yes, the AC is still hooked up. Why? I do not know, used it twice in the last 12 months. Blows cold.

alf

[SpeedracerIndy]

Originally posted by alf
Along the same lines, how many horses would i free up if i disconnect the belt to the AC Compressor?

Yes, the AC is still hooked up. Why? I do not know, used it twice in the last 12 months. Blows cold.

alf

My father has an 88 with a/c. While changing the belts last winter, I took off the AC, and didn't put it back on until summer. I couldn't tell a difference at all. When the a/c is not on, the clutch is disengaged, and the pulley is spinning freely. I think the drag from that freely spinning pulley is very negligible. I think the main benefit would be a big weight reduction if you were to remove the entire a/c system.

[RoninLB]

upper cylinders and heads operate on the edge of the envelope with the fan connected. Engine oil that can take the heat are an issue, unless oil coking doesn't matter.

[Lorenfb]

Did someone mention HP without suggesting a chip?
This forum must be getting too uptight.

[RoninLB]

Originally posted by Lorenfb
Did someone mention HP without suggesting a chip?

LOL

[Bob's Flat-Six]

I'm not sure on our 911's but on a Cummins diesel (855 cu.in.) with 350 HP and around 1200 ft lbs of torque the fan's rob about 30HP.
I know it not apples to apples but 16HP on a flat-six sounds reasonable with all the blades and a lot less torque.

I would also NOT run a 911 without that fan even a short distance.

The diesels fan hardly ever turn's on. It has 11 gallons of coolant and just about as much oil with a big oil cooler and a big Turbo
It just doesn't corner as good as my SC

[RoninLB]

Originally posted by Bob's Flat-Six
I know it not apples to apples but 16HP on a flat-six sounds reasonable with all the blades and a lot less torque.

Yep.. sure does.

The Air C # is scary

[Randy Webb]

The definitive stmt:

from Ludvigson, Excellence Was Expected, 1st ed.:

On the 1963 911, the cooling fan took only 4.7% of the 901's gross engine output - p. 402, Ch. 16

[RoninLB]

Originally posted by Lorenfb
Did someone mention HP without suggesting a chip?
This forum must be getting too uptight.

hey Loren..
did you catch my reply in the cup holder thread.. LOL

God, I'm excited!

[Bill Verburg]

Why does it take so much HP?

If you read through the thread I posted you would note that @ 6100rpm the 3.6 fan is moving 1010 liters of air /sec = 8.3hp

An HVAC engineer friend and I did the calculations and they are correct thats what it takes to move that much air. That fan is moving a lot of air.

[SpeedracerIndy]

8.3hp isn't all that much though considering the amount of air that it's moving. Even with a cooling fan that is 10% more efficient, you would only be saving about 1hp.